Template for thin layer chromatography samples

ABSTRACT

A template for holding a chromatographic sheet while permitting the application of a series of liquid samples rapidly, and on a well defined area of fixed size, comprises a base plate adapted to receive a chromatographic sheet on its surface, an applicator plate mating with the base plate and adapted to lie on top of the sheet, and means for clamping the parts together to hold the sheet in place. The applicator plate and the base plate are hinged together and provided with latches for clamping them together. To provide wells for receiving liquid samples, the applicator plate has a plurality of bores therethrough within which are pressed plastic bushings for engaging the chromatographic sheet without damaging its delicate surface. Also, two stop springs ease the movement of the applicator plate into register with the base plate so as to avoid damage to the chromatographic sheet. The base plate is provided with an abutment against which an edge of a chromatographic sheet is precisely positioned. The hinges are readily disengaged and reengaged to permit cleaning of the parts. Evaporation of solvent from the samples can be assisted by providing a suitable electrical heater in the base plate.

United States Patent LaFleur et al.

[ Dec. 25, 1973 TEMPLATE FOR THIN LAYER CHROMATOGRAPHY SAMPLES [75]lnventors: Bob A. LaFleur; Robert J. OBrien,

both of Rochester, NY.

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

[22] Filed: Oct. 14, 1971 [21] Appl. No.: 189,112

[52] US. Cl. 118/503, 118/504 [51] Int. Cl. B05c 11/12 [58] Field ofSearch 118/504, 505, 406, 118/301, 503; ll7/8.5, 38; 101/126; 83/454,459, 465; 408/241 B, 72; 51/310, 262; 269/91, 93, 92, 94, 87.2, 87.3

[56] References Cited UNITED STATES PATENTS 3,109,641 ll/l963 La Pierre118/504 X 2,899,928 8/1959 Pataky 118/505 X 3,380,434 4/1968 Faber118/504 X 2,704,992 3/1955 Schell 118/49 3,280,794 10/1966 Rosenberg118/301 3,161,543 12/1964 Borders et a1. 118/503 X 2,125,457 8/1938Merritt 117/38 X 3,685,916 8/1972 Loomis. 408/72 1,575,564 3/1926Fleming 118/415 Primary Examiner-Morris Kaplan Att0rneyWilliam T. Frenchet a1.

A template for holding a chromatographic sheet while permitting theapplication of a series of liquid samples rapidly, and on a well definedarea of fixed size, comprises a base plate adapted to receive achromatographic sheet on its surface, an applicator plate mating withthe base plate and adapted to lie on top of the sheet, and means forclamping the parts together to hold the sheet in place. The applicatorplate and the base plate are hinged together and provided with latchesfor clamping them together. To provide wells for receiving liquidsamples, the applicator plate has a plurality of bores therethroughwithin which are pressed plastic bushings for engaging thechromatographic sheet without damaging its delicate surface. Also, twostop springs ease the movement of the applicator plate into registerwith the base plate so as to avoid damage to the chromatographic sheet.The base plate is provided with an abutment against which an edge of achromatographic sheet is precisely positioned. The hinges are readilydisengaged and reengaged to permit cleaning of the parts. Evaporation ofsolvent from the samples can be assisted by providing a suitableelectrical heater in the base plate.

ABSTRACT 9 Claims, 3 Drawing Figures TEMPLATE FOR THIN LAYERCHROMATOGRAPHY SAMPLES BACKGROUND OF THE INVENTION 1. Field of theInvention The present invention relates to a novel improved apparatusfor rapidly applying samples to a chromatographic sheet.

2. The Prior Art The chemical analysis of many compositions has beenconducted successfully by spotting the compositions on a thin sheet ofpaper, glass or synthetic resin which carries an adsorbent coating on asurface thereof, such as powdered cellulose, silica gel, alumina, nylon,polyethylene, etc. Reference is made to US. Pat. Nos. 3,418,152;3,418,158; 3,492,155; 3,498,830 for more details.

After the sheet has been spotted with one sample or a series of spacedsamples and dried, it is dipped into a chromatographic eluant solventsuch as benzene, alcohols, chloroform, water, etc. and developed in aclosed chamber such as that shown in US. Pat. No. 3,413,842. The solventmigrates along the sheet, carrying the components of the sample spotswith it, with individual components travelling at different rates. Thecomponents are identified by comparison with a chromatograph of a knowncomposition.

Usually the spots have been applied by dissolving the unknowncomposition in a volatile solvent such as methyl or ethyl alcohol, oracetone to form a liquid sample, and then repeatedly dabbing smallquantities of the sample on the chromatographic sheet while allowingsolvent to evaporate between dabs. This is a slow and expensiveprocedure, and also is disadvantageous because it is difficult toconfine the sample to a well defined small area. I

In US. application Ser. No. 176,627 which was filed on or about Aug. 31,1971 by AD. Baitsholts, N.E. Jackobs and I. Timrots, entitled TemplateFor Applying Samples To A Thin Layer Chromatographic Sheet," there isdisclosed a novel apparatus and method for solving the above problems ofthe prior art. The present invention is an improved template apparatus,which is so constructed as to prevent damage to the thin layer surfaceof a chromatographic sheet while assuring that a seal is maintained atthat surface to confine the sample spots to a small area. Our novelapparatus is also so constructed that a chromatographic sheet can beprecisely and quickly positioned for receiving samples; and that theparts can be easily and rapidly disassembled for cleaning, and just asrapidly and easily reassembled for use.

SUMMARY OF THE INVENTION As in the application mentioned above, ournovel apparatus comprises a base plate adapted to receive achromatographic sheet on its surface, an applicator plate mating withthe base plate and adapted to lie on top of the sheet, and means forclamping the various parts together to hold the chromatographic sheet inplace.

The applicator plate has at least one hole therein acting as a well forreceiving a liquid sample solution, and advantageously a plurality ofsuch holes such as up to 19 or more lying on a straight line so that allsamples are applied to a chromatographic sheet the same distance fromits edge.

Evaporation of the solvent from the sample to leave a defined dry spotof the substance to be analyzed occurs while it is confined to the well,and may be accomplished under ambient conditions. or by providing meansfor heating the apparatus if a greater evaporation rate is desired.

The improvements of our invention over the prior application include thehinging of the applicator plate to the base plate for pivotting movementinto and out of register with the base plate, and the provision of oneor more rapid acting latches on one of the plates which are movable intoand out of engagement with the other of the plates for clamping achromatographic sheet between the plates. The hinge mountingadvantageously comprises two half hinges which can be moved into and outof engagement with one another to separate the plates for cleaning.

Another improvement lies in the provision of abutment means, such asproperly positioned dowels and/or shoulders on the base plate, againstwhich an edge of a chromatographic sheet is accurately positioned forreceiving samples.

When moving the applicator plate into position on top of achromatographic sheet, a seal with the surface of the chromatographicsheet at each hole or bore is assured by a bushing of resilient plasticmaterial such as Teflon polytetrafluorethylene within each bore andprotruding therefrom. The resilience of each bushing causes it to yieldslightly when engaging the chromatographic sheet, and thus avoidsremoving surface material. Additionally, the surface is protectedagainst damage by providing resilient stop means, such as two coilsprings, which are carried by one of the plates and are adapted toengage the other plate just before the applicator plate contacts thechromatographic sheet, so as to ease or arrest its movement and preventharmful impact against the sheet.

THE DRAWINGS FIG. 1 is a plan view showing our novel template apparatusin open position ready to receive a chromatographic sheet;

FIG. 2 is a plan view showing the applicator plate closed into operatingposition on top of the base plate as though a chromatographic sheet werepositioned therein; and

FIG. 3 is a cross sectional view on an enlarged scale taken along theline 3-3 in FIG. 2.

THE SPECIFIC EMBODIMENT Referring to the drawings it will be seen thatour novel apparatus comprises a base plate 11, and an applicator plate13 which is hingedly mounted on the base plate by cooperating halfhinges l5, 17 on one side of the base plate, and 19, 21 on a side of theapplicator plate. The half hinges 19, 21 are laterally slidable on hingepins 20 for disengagement of applicator plate 13 from base plate 11, andreengagement therewith.

Both plates 11 and 13 can be constructed of a metal such as stainlesssteel to resist corrosion by sample solutions. If desired, base plate 11can be formed of two elements, the main part 11a being stainless steel,and extension 11b being formed of a lighter and less expensive materialsuch as a plastic, for example, a phenolformaldehyde resin. The twoelements can be bolted together.

Base plate 11 is provided with two protruding abutment pins 23 arrangedon a line parallel to and spaced slightly from the hinged edge of theplate for contact with an edge of a rectangular chromatographic sheetwhich is positioned on top of the base plate for receiving samples.Instead of pins 23, a shoulder may be formed by milling or otherwiseproviding a concave or depressed area in the base plate within which thechromatographic sheet lies. The side edges of the chromatographic sheetare also guided and positioned properly by engagement with a pair ofside shoulders 27 and 29. A slight flaring of these shoulders at theirentrance ends will ease the introduction of a chromatographic sheet.

When the chromatographic sheet has been positioned on base plate 11, theapplicator plate 13 is swung over on top of the sheet in position forapplying samples. Just before the applicator plate reaches the sheet itencounters a pair of stop springs 31 embedded in the sides of the baseplate which case the downward movement and prevent the applicator platefrom damaging the thin adsorbent layer on the chromatographic sheet. I

Applicator plate 13 is provided with a plurality of holes or bores 35therethrough which are aligned with one another, and spaced slightlyapart, in position for applying samples to a series of areas of thechromatographic sheet which are evenly spaced from shoulder 23 and thecoactng edge of the chromatographic sheet. Holes 35 are frusto conicalin their upper portions, and merge smoothly at their lower portions intocylindrical portions.

As shown in FIG. 3, each bore 35 comprises a bushing 37 which protrudesa short distance beyond that surface of applicator plate 13 whichregisters with base plate 11, so as to engage the surface of thechromatographic sheet and form a tight seal therewith, thus pre' ventingmigration of a liquid sample outside the circular area of engagement.The protruding part of each bushing is bevelled to assure tightengagement with a sheet. The bushings 37 should be a resilient material,for example a plastic such as Teflon polytetraflumethylene,polyethylene, polypropylene, or other well known plastic materials whichwill resist the action of solvents employed for applying the samples tothe chromatographic sheet.

In order to expedite evaporation of solvent from the samples, base plate11 is provided with a lateral bore within which is positioned acylindrical electrical resistance heating element 41. A rheostat can beprovided for regulating the temperature so as to avoid charring ormelting the chromatographic sheet.

When using the apparatus the chromatographic sheet is positioned on baseplate 11 with its leading edge against abutments 23 and its side edgesconfined between abutments 27 and 29. Applicator plate 13 is then swunginto position with all of the bushings 37 in contact with the sheet, andthe latches 43, are actuated into engagement with pins 47, 49 to assuresuch contact. Then the full amount of each sample, dissolved in itssolvent, is introduced into each sample hole 35 and heat is applied fromthe heater 41 to cause the solvent to evaporate and leave a well definedcircular area ofdried solvent on the chromatographic sheet. Then thelatches are disengaged and the plates are swung apart from one anotherso that the chromatographic sheet can be removed for subsequentintroduction into elution apparatus in a conventional way.

With this construction there is no longer reason to apply a sample byrepeatedly dabbing it onto the surface of a chromatographic sheet over along period of time, because the full amount of a sample can beintroduced at one time and the solvent allowed to evaporate therefrom inone fifth the time or less. When a series of samples are to be analyzedon the same chromatographic sheet they can all be introduced in fullvolume at the same time through a series of the sample holes 31 and thenallowed to dry much more rapidly than was previously possible.

Rapid application of samples, as by the above described apparatus andmethod is of prime importance in clinical laboratories or drugdetoxification centers where thousands of samples are chromatographedevery week. Where it previously required 5 minutes to apply each sample,using a hot air dryer between dabs of only 2-3 microliters, it is nowpossible to apply each sample in less than 15 seconds.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:

1. Apparatus for applying liquid samples to a' chromatographic sheetcomprising, in combination,

a base plate adapted to receive a chromatographic sheet on the surfacethereof; an applicator plate hingedly mounted on said base plate formovement into and out of register with the top of said base plate, saidapplicator plate being adapted to lie on such a sheet and having aplurality of holes therethrough for receiving a plurality of liquidsamples to spot said sheet; and

said applicator plate comprising a bushing of resilient material in eachof said holes and projecting therefrom in position to engage and to forma tight seal with such a sheet.

2. Apparatus in accordance with claim 1 wherein said base plate hasabutment means thereon adapted to engage an edge of such achromatographic sheet to position such a sheet for receiving a sample.

3. Apparatus in accordance with claim 1, also comprising resilient stopmeans carried by one of said plates and adapted to engage the other ofsaid plates during movement into register with one another, to arrestsuch movement and prevent harmful impact against such a chromatographicsheet.

4. Apparatus in accordance with claim 1 wherein said base plate and saidapplicator plate each has half hinge means thereon, said half hingemeans being movable into and out of engagement with one another fordetaching said applicator plate from said base plate at will.

5. Apparatus in accordance with claim 1 wherein said base plate hasabutment means thereon adapted to engage an edge of such achromatographic sheet to position such a sheet for receiving a sample;

said apparatus also comprising resilient stop means carried by one ofsaid plates and adapted to engage the other of said plates duringmovement into register with one another, to arrest such movement andprevent harmful impact against such a chromatographic sheet.

6. Apparatus in accordance with claim 5 wherein said base plate and saidapplicator plate each has half hinge means thereon, said half hingemeans being movable into and out of engagement with one another fordetaching said applicator plate from said base plate at will.

7. Apparatus in accordance with claim 2, wherein said holes arranged ina straight line parallel to said abutment means for applying a pluralityof samples to such a chromatographic sheet along a straight lineparallel to such edge thereof.

8. Apparatus in accordance with claim 1, also comprising latch means onone of said plates movable into and out of engagement with the other ofsaid plates and acting to clamp a chromatographic sheet between said pinmeans.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,78,7 Dated December 25, 1973 Bob A. LaFleur, Robert J. O'Brien It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Claim 7, line 2, after "holes insert -.-are--.f

Claim 9, line 1, change "8" to --6--.

Signed and sealed this 30th day" ,of April 1 97b (SEAL) Attest:

EDWARD I-Z.l-LEICHJ5R,JR. c. EL TE-STEELE IL ANN AttestingOfficerCommissioner of Patents

1. Apparatus for applying liquid samples to a chromatographic sheetcomprising, in combination, a base plate adapted to receive achromatographic sheet on the surface thereof; an applicator platehingedly mounted on said base plate for movement into and out ofregister with the top of said base plate, said applicator plate beingadapted to lie on such a sheet and having a plurality of holestherethrough for receiving a plurality of liquid samples to spot saidsheet; and said applicator plate comprising a bushing of resilientmaterial in each of said holes and projecting therefrom in position toengage and to form a tight seal with such a sheet.
 2. Apparatus inaccordance with claim 1 wherein said base plate has abutment meansthereon adapted to engage an edge of such a chromatographic sheet toposition such a sheet for receiving a sample.
 3. Apparatus in accordancewith claim 1, also comprising resilient stop means carried by one ofsaid plates and adapted to engage the other of said plates duringmovement into register with one another, to arrest such movement andprevent harmful impact against such a chromatographic sheet. 4.Apparatus in accordance with claim 1 wherein said base plate and saidapplicator plate each has half hinge means thereon, said half hingemeans being movable into and out of engagement with one another fordetaching said applicator plate from said base plate at will. 5.Apparatus in accordance with claim 1 wherein said base plate hasabutment means thereon adapted to engage an edge of such achromatographic sheet to position such a sheet for receiving a sample;said apparatus also comprising resilient stop means carried by one ofsaid plates and adapted to engage the other of said plates duringmovement into register with one another, to arrest such movement andprevent harmful impact against such a chromatographic sheet. 6.Apparatus in accordance with claim 5 wherein said base plate and saidapplicator plate each has half hinge means thereon, said half hingemeans being movable into and out of engagement with one another fordetaching said applicator plate from said base plate at will. 7.Apparatus in accordance with claim 2, wherein said holes arranged in astraight line parallel to said abutment means for applying a pluralityof samples to such a chromatographic sheet along a straight lineparallel to such edge thereof.
 8. Apparatus in accordance with claim 1,also comprising latch means on one of said plates movable into and outof engagement with the other of said plates and acting to clamp achromatographic sheet between said plates with said bushings engagingsaid chromatographic sheet.
 9. Apparatus in accordance with claim 8wherein said half hinge means on one of said plates comprises hinge pinmeans projecting laterally in one direction therefrom adjacent andparallel to an edge thereof, and wherein said half hinge means on theother of said plates comprises bearing means on said other oF saidplates extending laterally thereof adjacent and parallel to an edgethereof and slideable on and off said hinge pin means.